Liquid-crystalline medium

Abstract

The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy, which comprises at least one compound of the formula (I) in which R 0 , R 1 , A 1 , Z 1 and m have the meanings indicated in Claim 1 , and to the use thereof for an active-matrix display based on the ECB, PALC or IPS effect.

1. A liquid-crystalline medium based on a mixture of polar compounds having negative dielectric anisotropy, comprising a compound of formula I 
       
         
           
           
               
               
           
         
         in which 
         R 0  and R 1  each, independently of one another, denote H, an alkyl or alkenyl radical having up to 15 C atoms, which is unsubstituted, monosubstituted by CN or CF 3 , or at least monosubstituted by halogen, in which optionally one or more CH 2  groups are replaced by —O—, —S—, 
       
       
         
           
           
               
               
           
         
       
       —C≡C—, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another,
 A 1  a) denotes a 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH 2  groups are optionally replaced by —O— or —S—,
 b) denotes a 1,4—phenylene radical, in which one or two CH groups are optionally replaced by N, 
 c) denotes piperidine-1,4-diyl-, 1,4-bicyclo[2.2.2]octylene-, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl or fluorene-2,7-diyl, 
 where A 1  is optionally mono- or polysubstituted by halogen atoms, 
 
 Z 1  denotes —CO—O—, —O—CO—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —CH 2 CH 2 , —(CH 2 ) 4 —, —C 2 F 4 —, —CH 2 CF 2 —, —CF 2 CH 2 —, —CF═CF—, —CH═CF—, —CF═CH—, —CH═CH—, —C≡C— or a single bond, and 
 m denotes 0, 1 or 2. 
 
     
     
       2. A liquid-crystalline medium according to  claim 1 , which comprises at least, one compound of formula , I1 , I2, I3, I4, I5, I6, I7, I8, I9, I10, I11, I12, I13, I14, I15, I16, I17 or I18 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         in which R 0  and R 1  have the meanings indicated for formula I. 
       
     
     
       3. A liquid-crystalline medium according to  claim 1 , wherein R 0  denotes H. 
     
     
       4. A liquid-crystalline medium according to  claim 2 , which comprises at least one compound of formula I1. 
     
     
       5. A liquid-crystalline medium according to  claim 1 , further comprising one or more compounds of formulae IIA and/or IIB: 
       
         
           
           
               
               
           
         
         in which 
         R 2  denotes an alkyl or alkenyl radical having up to 15 C atoms, which is unsubstituted, monosubstituted by CN or CF 3 , or at least monosubstituted by halogen, in which optionally one or more CH 2  groups are replaced, independently of one another, by —O—, —S—, 
       
       
         
           
           
               
               
           
         
       
       —C≡C—, —CO—, —CO—O—, —O—CO— or —O—CO—O— in such a way that O atoms are not linked directly to one another,
 p denotes 1 or 2, and 
 v denotes 1 to 6. 
 
     
     
       6. A liquid-crystalline medium according to  claim 1 , further comprising one or more compounds of formula III 
       
         
           
           
               
               
           
         
         in which 
         R 31  and R 32  each, independently of one another, denote a straight-chain alkyl, alkenyl, alkylalkoxy or alkoxy radical having up to 12 C atoms, and 
       
       
         
           
           
               
               
           
         
       
     
     
       7. A liquid-crystalline medium according to  claim 1 , which comprises two, three, four or more compounds of formula I. 
     
     
       8. A liquid-crystalline medium according to  claim 1 , wherein the proportion of the compounds of formula I in the mixture as a whole is at least 5% by weight. 
     
     
       9. A liquid-crystalline medium according to  claim 5 , wherein the proportion of the compounds of formulae IIA and/or IIB in the mixture as a whole is at least 20% by weight. 
     
     
       10. A liquid-crystalline medium according to  claim 5 , wherein the proportion of the compounds of formula III in the mixture as a whole is at least 5% by weight. 
     
     
       11. A liquid-crystalline medium according to  claim 6 , which essentially consists of 5-30% by weight of one or more compounds of formula I and 20-70% by weight of one or more compounds of formulae IIA and/or IIB. 
     
     
       12. An electro-optical display with active-matrix addressing based on the ECB, PALC or IPS effect, which contains, as dielectric, a liquid-crystalline medium according to  claim 1 . 
     
     
       13. An electro-optical display with active-matrix addressing based on the ECB, PALC or IPS effect, which contains, as dielectric, a liquid—crystalline medium according to  claim 11 . 
     
     
       14. A liquid-crystalline medium according to  claim 5 , further comprising one or more compounds of formula III 
       
         
           
           
               
               
           
         
         in which 
         R 31  and R 32  each, independently of one another, denote a straight-chain alkyl, alkenyl, alkylalkoxy or alkoxy radical having up to 12 C atoms, and 
       
       
         
           
           
               
               
           
         
       
     
     
       15. An electro-optical display with active-matrix addressing based on the ECB, PALC or IPS effect, which contains, as dielectric, a liquid-crystalline medium according to  claim 14 . 
     
     
       16. A liquid-crystalline medium according to  claim 1 , which comprises at least one compound of formula Ia, Ib, Ic, Id, le, If or Ig 
       
         
           
           
               
               
           
         
       
     
     
       17. A liquid-crystalline medium according to  claim 6 , wherein the compound of formula III is a compound of formula IIIa, IIIb, IIIc, IId, IIIe or IIIf 
       
         
           
           
               
               
           
         
         in which 
         alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and 
         alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms. 
       
     
     
       18. A liquid-crystalline medium according to  claim 1 , which comprises at least one compound of formula Ia 
       
         
           
           
               
               
           
         
       
     
     
       19. A liquid-crystalline medium according to  claim 5 , which comprises at least one compound of formula Ia 
       
         
           
           
               
               
           
         
       
     
     
       20. A liquid-crystalline medium according to  claim 6 , which comprises at least one compound of formula Ia